Now Trump has reaffirmed his threat – and added that maybe it wasn’t tough enough.

Inside North Korea: The pictures Kim Jong-un doesn't want you to see

Since 2008, photographer Eric Lafforgue ventured to North Korea six times. Thanks to digital memory cards, he was able to save photos that was forbidden to take inside the segregated state

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Eric Lafforgue/Exclusivepix Medi

Taking pictures in the DMZ is easy, but if you come too close to the soldiers, they stop you

He also says that the North should be "very, very nervous" if it delivers on its planned attack.

And he’s piled the pressure on China again, asking Beijing to rein in its neighbour and longstanding ally.

If the North Koreans don’t “get their act together” he said, their country will be in trouble "like few nations have ever been".

The tough talk comes as Senator Lindsey Graham, a former candidate for President, warned that Trump was ready for a pre-emptive strike on Kim.

GETTY

FACE OFF: Donald Trump, right, and Kim Jong-un, left

And he called on his colleagues in Congress to rally round the President if he did, even though he could strike without their permission.

He told them: "It would be very smart if the Congress could come together and tell the president 'you have our authorization'.

"That would sent a signal to North Korea and China, that would probably do more good to avoid war than anything."

Brainwashed citizens CELEBRATE the launch of Kim Jong-un's ICBM

Kim Jong-un launched a sick celebration of the successful test launch of the country's first intercontinental ballistic missile. Thousands thronged to Kim Il-sung Square in capital city Pyongyang for displays of dancing and fireworks as the world plummets into disorder

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REUTERS

People celebrate the successful missile test as they watch on the big screen

Asked if he would consider a pre-emptive strike against North Korea, Trump said, "We'll see what happens."

He added that the North should be nervous "because things will happen to them like they never thought possible".

Yet he left the door open for talks, saying he would "always consider negotiations" despite the failure of past attempts.